no one knows what your tolerance to medications are so asking if 15ml is enough is beyond us
5ml of tussionex has about 10mg worth of hydro so itll be 30mg of hydro but keep in mind it has chlorpheniramine in it also, think its a anti histamine if memory recalls
15ml can be pretty potent if you dont have tolerance i would start at 5ml then take another 5 ml and so on until you feel good
you can take more, never less
dont recommend you take anything else either with like alcohol etc